Apparatus for manufacturing flexible packages having slide closures

ABSTRACT

Horizontal form fill seal apparatus for making flexible packages with slider fastener closures is provided. A fastener track is applied in-line with a plastic web and is bonded thereto at the same time that a peel seal is formed. All package components are brought together at the point of fill.

[0001] CROSS REFERENCE TO RELATED APPLICATIONS

[0002] This application is a continuation-in-part of U.S. patentapplication Ser. No. 09/836,984, filed Apr. 18, 2001, (Docket No. 67293)and U.S. patent application Ser. No. 09/945,557, filed Aug. 30, 2001,(Docket No. 67314), which is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] The present invention pertains to the manufacture of flexiblepackages, such as plastic bags, and in particular to packages havingfastener closures employing sliders.

[0005] 2. Description of the Related Art

[0006] With the recent emphasis in providing consumers with bulkquantities of various commodities, such as food products, reclosablepackages have become increasingly popular. One of the most popular meansof providing reclosability is to employ zippers of various types,particularly zippers which are compatible with flexible packages ofplastic film construction. Manufacturers of food products and othercommodities are concerned with filling the contents of a flexiblepackage as quickly and economically as possible. It is important thatthe opening provided by the fastener be made as large as practicallypossible. Consumers or other end users also prefer large sized openingsfor easy extraction of products from the package interior. Even withlarge openings, however, products within the package may interfere withfastener operation when product poured or otherwise dispensed from thepackage becomes entrained in the fastener components.

[0007] Other improvements to flexible reclosable packages are beingsought. For example, when handling products comprised of numerous smallpieces, such as shredded cheese or cereal, for example, it is generallydesirable to have the package formed into a pouch which is open at oneend, or along one side, so as to allow product to be poured or shakenthrough the reclosable opening. It is desirable that the product beallowed to freely flow past the reclosable opening. Preferably, the pathtaken by the product within the package should be made as smooth aspossible.

[0008] Although improvements have been made in the art of plasticwelding and joining, manufacturers of consumer products employing highspeed production techniques are continually seeking improved packageforming methods and equipment.

SUMMARY OF THE INVENTION

[0009] It is an object of the invention to provide apparatus formanufacturing improved, shrouded and unshrouded flexible packages.

[0010] Another object of the invention is to provide apparatus formaking reclosable packages having fastener sliders which are protectedas the package contents are poured out or otherwise extracted.

[0011] A further object of the invention is to provide apparatus formaking a reclosable plastic package having a slider fastener withimproved containment of the slider in a manner which also optimizes thesize of the bag opening.

[0012] A further object of the invention is to provide apparatus formaking a plastic bag having a slider fastener with an improved end“crush” stop of the fastener tracks.

[0013] These and other objects of the invention are attained in ahorizontal form-fill seal machine for the in-line manufacturing of foodpackages with shrouded, mated fastener tracks and slider closures, thatcomprises a supply of web material that extends in a machine directionthat defines a serial succession of package sidewalls and extends in themachine direction. A supply of mated fastener tracks, which include afirst track with a shorter flange mated to a second track with a longerflange. A folding member which receives web material. A web drive thattransports web material over folding member in the machine direction,folding web material into overlying side-by-side portions, one againstthe other, to form a continuous succession of folded package portions,which extend in the machine direction and which have pairs of overlyingfirst and second package sidewalls that have overlying free edges withshroud portions at the free edges. A slider member mateable with matedfastener tracks for movement along mated fastener tracks in oppositedirections to open and close mated fastener tracks. A sliderinstallation member that is inserted in the slider member onto matedfastener tracks. Fastener seal bars extend in the machine direction,that seal a portion of each flange of fastener tracks to first sidewall,and leave the flanges free of attachment to the second package sidewall.Side seal bars extend at an angle to machine direction, and sealportions of said package sidewalls together to form respective sideseals of the food package. A filler member filling product into package.Sidewall sealing means that seal second package sidewall to second trackflange and a shroud sealing member that seals the free edges of thepackage sidewalls to form a shroud enclosing the fastener tracks, toform a completed food package.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a fragmentary front elevational view of a flexiblepackage according to principles of the present invention;

[0015]FIG. 2 is a fragmentary cross-sectional view taken along the line2-2 of FIG. 1;

[0016]FIG. 3 is a fragmentary end view indicated by line 3-3 of FIG. 1;

[0017]FIG. 4 is fragmentary front elevational view showing constructionof the flexible package;

[0018]FIG. 5 is a top plan view of the slider member;

[0019]FIG. 6 is a front elevational view thereof;

[0020]FIG. 7 is an elevational view from one end thereof;

[0021]FIG. 8 is an elevational view from the other end thereof;

[0022]FIG. 9 is an end view of a fastener track subassembly;

[0023]FIG. 10 is a cross-sectional view, in schematic form, taken alongthe line 10-10 of FIG. 1 with the slider moved to the left;

[0024]FIG. 10a is a fragmentary view, of FIG. 10 shown on an enlargedscale;

[0025]FIGS. 10b and 10 c show alternative seal constructions;

[0026]FIG. 11 is a fragmentary front elevational view showing contentsbeing poured from the flexible package;

[0027]FIG. 12 is a fragmentary front elevational view showing contentsof a prior art package;

[0028]FIG. 13 is a fragmentary front elevational view of anotherflexible package according to principles of the present invention;

[0029]FIG. 14 is a front elevational view of another flexible packageaccording to principles of the present invention;

[0030]FIG. 15 is a fragmentary elevational view of a shrouded flexiblepackage constructed according to principles of the present invention;

[0031]FIG. 16 is a fragmentary cross-sectional view taken along line16-16 of FIG. 15;

[0032]FIG. 17 is a fragmentary end view of the package of FIG. 15;

[0033]FIG. 18 is a fragmentary elevational view of a further embodimentof a flexible package constructed according to principles of the presentinvention;

[0034]FIG. 19 is a fragmentary elevational view of another embodiment ofa shrouded flexible package;

[0035]FIG. 20 is a cross-sectional view taken along the line 20-20 ofFIG. 15;

[0036]FIG. 21 is a cross-sectional view similar to that of FIG. 20,shown with the schematic depiction of tooling to form the flexiblepackage;

[0037]FIG. 22 is a fragmentary elevational view of a further embodimentof a shrouded flexible package;

[0038]FIG. 23 is a fragmentary elevational view of an additionalembodiment of a shrouded flexible package;

[0039]FIG. 24 is a cross-sectional view similar to that of FIG. 20 butshowing an alternative shroud construction;

[0040]FIG. 25 is a fragmentary elevational view of a further embodimentof a shrouded flexible package;

[0041]FIG. 26 is a perspective view of apparatus for constructingflexible packages according to principles of the present invention;

[0042]FIG. 27 is a side elevational view thereof;

[0043]FIG. 28 is a fragmentary view showing the plastic web;

[0044]FIG. 29 shows the plastic web being folded;

[0045]FIG. 30 shows a portion of FIG. 29 taken on an enlarged scale;

[0046]FIG. 31 is a fragmentary view of the lower right corner of FIG.30, taken on an enlarged scale;

[0047]FIG. 32 shows an operation performed on the bottom of the webportions;

[0048]FIG. 33 shows a portion thereof taken on an enlarged scale;

[0049]FIG. 34 shows end stop and slider work stations of FIG. 26, takenon an enlarged scale;

[0050]FIG. 35 is a cross-sectional view taken along the line 35-35 ofFIG. 30;

[0051]FIG. 36 is a cross-sectional view taken along the line 36-36 ofFIG. 30;

[0052]FIG. 37 shows a vertical sealing work station portion of FIG. 26;

[0053]FIG. 38 shows a portion thereof on an enlarged scale;

[0054]FIG. 39 shows one example of a flexible package constructed withapparatus according to principles of the present invention;

[0055]FIG. 40 shows a severing work station of FIG. 26, on an enlargedscale;

[0056]FIG. 41 is a perspective view showing filling of a flexiblepackage;

[0057]FIG. 42 is a side elevational view thereof;

[0058]FIG. 43 is a top plan view thereof;

[0059]FIG. 44 is a diagrammatic view of FIG. 42,

[0060]FIG. 45 shows a top sealing work station of FIG. 26;

[0061]FIG. 46 is a cross-sectional view taken along the line 46-46 ofFIG. 45; and

[0062]FIG. 47 is a cross-sectional view taken along the line 47-47 ofFIG. 39.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0063] Referring now to the drawings and initially to FIGS. 1-8, animproved flexible package is generally indicated at 10. The terms“package” and “bag,” are used interchangeably and are not intended torefer to any relative size of the finished item.

[0064] Flexible package 10 preferably comprises a plastic bag havingfront and back panels 12, 14 joined together at the left end by a sideseal 20 and at the right end by a side seal 22. Side seal 20 ispreferably of conventional conduction heat-sealed construction, having agenerally constant width throughout. If desired, side seal 20 can beemployed on both sides of the flexible package. Panels 12, 14 arefurther joined together at their bottom ends by a bottom seal 24 (seeFIG. 10) extending between side seals 20, 22, as is known in the art.Alternatively, the bottom seal can be replaced by a fold line withpanels 12, 14 being formed from a continuous sheet of plastic material.

[0065] The upper end of flexible package 10 features a reclosableopening including a slide fastener arrangement with fastener tracks 26,28 and a slider 30, all preferably of polyolefin material. The slider 30is slidable along the fastener tracks, causing the fastener tracks tointerlock or mate (as shown in FIG. 2) for closure of the flexiblepackage and to unmate or separate to open the flexible package foraccess to contents in the package interior. As will be seen herein,features associated with the fastener slider arrangement allow anunprecedented enlarged opening of the flexible package. The enlargedpackage opening made possible by the present invention benefitsmanufacturers filling the package, as well as consumers dispensingproduct from the interior of the flexible package. In the preferredembodiment shown, the fastener tracks are also referred to as “zipper”tracks.

[0066] The flexible package according to principles of the presentinvention has found immediate commercial acceptance for use with foodproducts, including perishable food products, such as cheese.Accordingly, it is generally preferred that the flexible packageincludes a hermetic seal 36 in the form of a peelable seal as taught incommonly assigned U.S. Pat. Nos. 5,014,856; 5,107,658 and 5,050,736, thedisclosures of which are incorporated by reference as if fully set forthherein.

[0067] As mentioned above, flexible package 10 preferably comprises abag having panels 12, 14 formed from plastic sheet material. The sheetmaterial can be of a single material type, such as polyolefin materialsincluding polyethylene and polypropylene, but preferably comprises alaminate assembly of several different material types, as is known inthe art to provide a barrier to moisture as well as certain gases, suchas oxygen or inert fillers of the types used with food products. Othertypes of laminate films, such as those known in the art to preserve foodfreshness, may be employed. Where the contents of the flexible packageare not perishable or where other considerations may dictate, the panels12, 14 can be constructed without regard to gas or vapor barrierproperties. FIGS. 2 and 3 indicate that it is generally preferred thatthe fastener tracks be joined to web-like flanges which, in turn, arejoined to panels 12, 14 as will be described below with reference toFIG. 10.

[0068] Referring now to FIGS. 5-8, fastener slider 30 has a top wall 44,a shorter side wall 46 and a longer side wall 48, cooperating to definean internal cavity 50 for receiving the fastener tracks 26, 28. As canbe seen by comparing the end views of FIGS. 7 and 8, a first end 54 ofthe slider defines a cavity which is generally rectangular. The opposedend 56 (shown in FIG. 8) defines a cavity which is generally arrowheador A-shaped, as indicated by reference numeral 50 b, conforming to theoutline of the interlocked fastener tracks shown in FIG. 2. When theslider 30 of FIG. 1 is moved to the right, end 56 is at the leading endof the slider and the fastener tracks 26, 28 are unlocked, thus openingthe flexible package 10. Conversely, as slider 30 of FIG. 1 is moved tothe left, end 54 (shown in FIG. 7) is made the leading end, and fastenertracks 26, 28 are interlocked in the manner indicated in FIG. 2, toclose the flexible package.

[0069] Referring again to FIGS. 2, 7 and 8, a number of featurescooperate to maintain slider 30 captive on fastener tracks 26, 28. Ascan be seen for example in FIG. 8, a pair of upwardly facing steppedportions 62 are formed on either side of the slider cavity. Inwardlyextending protrusions 64 are located at the other end of the slider.Protrusions 64 and stepped portions 62 engage the bottoms 26 a and 28 a(see FIG. 2) of fastener tracks 26, 28, as can be seen for example inFIG. 10. The engagement of the stepped portions 62 and the protrusions64 with the bottoms of the fastener tracks prevents the slider frombeing upwardly dislocated from the fastener tracks.

[0070] Referring to FIGS. 1, 3 and 13, the ends of the fastener tracksare deformed or “crushed” to form stops 68. Preferably, stops 68 areformed by the application of ultrasonically generated heat and pressureto the ends of fastener tracks 26, 28. It has been found that the use ofpresent day conduction heat sealing techniques does not provide thecontrol needed to attain the intricate, close tolerance design of stopmembers according to principles of the present invention. Further, ithas been found that the use of present day conduction heat sealingtechniques immediately adjacent previously formed stop members tends todistort the stop members, oftentimes to an extent rendering the stopmembers unacceptable from a quality control standpoint. As will be seenherein, stops 68 are configured for maximum efficiency, having thesmallest front elevational surface area (i.e., the surface area visiblein FIGS. 1 and 13, for example), which is adequate for containing slider30 on the fastener tracks.

[0071] Referring to FIG. 3, the sides of the fastener tracks aresoftened and compressed at stop faces or sides 72 so as to impart apre-selected width w and an upwelling displacement u above the uppersurfaces 26 b, 28 b of fastener tracks 26, 28 (see FIG. 2). The materialdisplaced above the upper surface of the fastener tracks interferes withthe top wall 44 and ends of slider 30 to limit its sideways travel.

[0072] With reference to FIG. 3, the slider stop 68 (that is, thedeformed portion of fastener tracks 26, 28) is carefully configured soas to avoid deformation of the bottom surfaces 26 a, 28 a of thefastener tracks. With reference to FIG. 1, the lower ends of thefastener tracks extend undeformed, substantially to the side edges 16,18 of the flexible package 10. FIG. 1 shows slider 30 “parked” at afully opened position, with end 56 contacting the stop 68 located at theright hand end 22 of the flexible package. Stop members 68 and theundisturbed bottom surfaces 26 a, 28 a of the fastener tracks in thearea of stop members 68 cooperate to captivate slider 30 on the fastenertracks, preventing its unintentional removal from flexible package 10.

[0073] It is preferred that the bottom edges 26 a, 28 a remainundeformed also for that portion extending beyond slider 30, andunderneath at least a portion of the right hand stop 68. With referenceto FIG. 3, a gap g is formed between the bottom edges of the fastenertracks and the top portion 81 of side seal 22. As can be clearly seen inFIG. 3, the stop 68, formed by ultrasonic techniques, is separated by asubstantial distance from the side seal, which is typically formed usingconduction heat seal techniques found to be incompatible with theprecise, high resolution ultrasonic techniques used to form stop 68. Asecond stop 68 formed at the left hand end 16 of flexible package 19 isconstructed in a similar fashion and extends beyond the end 54 of slider30 when the slider is moved fully to the left, closing the upper end ofthe flexible package. As will be explained in greater detail herein,separation of the “crush” operation performed on the fastener tracks toform stops 68 from the conduction heat sealing operation to form theenlarged side seals, allows stops 68 to take on a reduced size,effectively extending the size of the package opening, withoutsacrificing ability of the stops to effectively retain slider 30 on thefastener tracks.

[0074] Referring to FIGS. 1 and 4, side seal 22 includes an upperenlarged or tapered portion 80 having a width substantially greater thanthe lower end of side seal 22, sufficient to underlie the substantialentirety of slider 30 when the slider is fully moved to the “parked”position as shown in FIG. 1. The width of the enlarged, tapered portion80 ranges between 200% and 400% (or more for very narrow side seals,e.g., 2 mm or less) of the width s of side seal 22 and most preferablyranges between 250% and 300% of the side seal width s.

[0075] The enlarged, tapered end 80 of side seal 22 has a S-shaped ordouble re-entrant bend contour 84 which partly defines the packageinterior. With reference to FIG. 11, the curved edge 84 of the enlargedside seal portion 80 provides a smooth transition at the corner of thepackage opening, preventing product entrapment within the flexiblepackage. As those skilled in the art will appreciate, the smoothtransition at the opening corner is especially beneficial for flexiblepackages, where shaking techniques otherwise suitable for rigidpackages, are rendered largely ineffective by flexible panels 12, 14 andespecially panels of very thin, unsupported material which are likely tocollapse in use.

[0076] The smooth transition provided by curved edge 84 also deflects orguides product 86 away from slider 30 as product is poured or otherwiseremoved from flexible package 10. This prevents contamination of matingsurfaces of the slider and the fastener tracks, which would otherwisedeteriorate the ability of slider 30 to move freely, performinginterlocking and unlocking of the fastener tracks. As indicated in FIG.12, in prior art arrangements product 86 is allowed to freely contactthe bottom end of slider 30, a condition which is avoided by flexiblepackages according to principles of the present invention.

[0077] Preferably, fastener tracks 26, 28 are “crushed” to form stopmember 68, using conventional ultrasonic heating equipment which allowsfor a highly accurate shaping of the stop member as well as withdrawalof the deformation area away from the bottom surfaces 26 a, 28 a asshown, for example, in FIG. 3. As can be seen for example in FIG. 1, thewidth of stop member 68 is considerably less than the enlarged taperedportion 80 of side seal 22, and preferably is of a smaller width thanthat of the narrower major portion of side seal 22. With reference toFIG. 1, the width d of stop member 68 is less than the width s of sideseal 22. Preferably, stop member width d ranges between 50% and 200% ofthe width s of side seal 22. Preferably, the width w of the stop member68 (i.e., the “crush” dimension) ranges between 25% and 80% of the widthz of the fastener tracks, as illustrated in FIG. 3. The amount of upwarddisplacement or upwelling u is approximately at least as great as thethickness of upper wall 44. It should be kept in mind that the totalmass of the stop must be sufficient to hold the slider captive.

[0078] The stop member 68, in addition to having a reduced width d infront elevational view and a small width w in end view (see FIG. 3), hasa sufficiently smaller mass and frontal surface area than stops employedin the prior art. This construction allows the slider 30 to be moved toan extreme position immediately adjacent the edge 22 of flexible package10, thus maximizing the package opening, allowing for easier removal ofthe package contents. This reduced size of stop 68 also contributes tothe precision of the ultrasonic heating and formation of the stopmember, needed to attain required precise dimensions. Further, from amanufacturing standpoint, the dwell time to melt and shape the stop 68is substantially reduced, contributing to the overall efficiency for thepackage manufacturer.

[0079] Prior art stop members have been formed by “crushing” the entirefastener profile, including the bottom surfaces 26 a, 28 a. In addition,even if ultrasonic techniques are employed for the stop member, priorart side seals (formed using conduction heat seal techniques and muchlarger, oftentimes three to four times larger than side seals accordingto the present invention) were typically overlaid with the stop,contributing to a substantial distortion of the stop structure. Even ifthe prior art side seals were made to stop short of the fastener tracks,the relatively high level of conduction heating in the immediateproximity of the stop have been found to cause a distortion of the stop,degrading control over its size and shape. These disadvantages areavoided with practice of the present invention, where the small, compactsize of the stop is employed, and the gap g is formed between undeformedfastener bottom surfaces 26 a, 28 a and the enlarged seal portion 80.

[0080] Turning now to FIGS. 4, 9 and 10, and initially to FIG. 9, thefastener tracks are preferably formed from a sub-assembly generallyindicated at 70 in which the fastener tracks 26, 28 are provided withcorresponding fastener flanges 72, 74. The fastener flanges 72, 74 arecoextensive with the fastener tracks 26, 28 and take the form of aplastic web to be heat sealed to the panels 12, 14. As can be seen inFIG. 9, fastener flange 74 is shorter in height than fastener flange 72,so as to accommodate the preferred hermetic seal arrangement shown inFIG. 10.

[0081] The fastener flanges 72, 74 are heat sealed to panels 12, 14.With reference to FIGS. 4 and 10, fastener flange 72 is welded orotherwise mechanically sealed to panel 12 at weld band 78. As shown atthe upper portion of FIG. 10, the upper ends of panels 12, 14 are joinedto the outer outwardly facing surfaces of fastener flanges 72, 74 atpoints intermediate the fastener tracks and peelable seal 36. Band 36preferably comprises a hermetic peelable seal formed by the joinder ofpanel 14 to the inside face 72 a of fastener flange 72 (see FIGS. 10 and10a). Panel 12 is sealed to the opposite outside face of the fastenerflange as schematically indicated in FIG. 10. In FIG. 10a the componentsof the peelable seal 36 are shown, with film 12, which plays no part inthe preferred peelable seal, being shown in phantom.

[0082] Variations of the peelable seal are also contemplated by thepresent invention. For example, in FIG. 10b, the flanges 72, 74 of thefastener arrangement are joined with a peelable seal. The upper ends ofthese flanges are heat sealed to panels 12, 14 as shown. In FIG. 10c afurther alternative is shown with the peelable seal 36 being formed atthe joinder of lower portions of panels 12, 14. The upper portions ofpanels 12, 14 are heat sealed to fastener flanges 72, 74.

[0083] As will now be appreciated, the enlarged, tapered end portions 80of side seal 22 cooperate with other features of flexible package 10 toprovide a number of important advantages. More specifically, theenlarged tapered end portions 80 provide a smooth transition of theinterior of flexible package 10 preventing product entrapment in theslider and fastener track surfaces when product is poured or otherwisedispensed. In addition, the enlarged tapered portion 80 helps to secureslider 30 about tracks 26, 28 by maintaining a clearance from bottomsurfaces 26 a, 28 a of the fastener tracks. Further, the enlargedtapered portions 80 of side seals 22 strengthen and rigidify edgeportions of panels 12, 14 in the immediate area of the parked positionof slide 30.

[0084] Often, the greatest amount of force applied by the user to slider30 occurs at the closing of the slider, when the fastener tracks areunlocked or separated from one another. When the slider 30 is in themiddle of its travel along the fastener tracks, the user is providedwith a sensation of the proper direction of slider movement. However,when the slider 30 is in the parked position, and especially in the“parked open” position shown in FIG. 1, the user's initial applicationof force may be misdirected. The enlarged tapered portion 80 providesadded stiffness and rigidity to the flexible package at the initialpoint where pressure is applied to the slider, thus further contributingto the assurance that secure engagement will be maintained betweenslider 30 and the tracks 26, 28.

[0085] With reference to FIG. 4, a consumer desiring to close theflexible package will grasp the enlarged side seal portion 80, pullingin the direction of arrow 81 while pulling or pushing slider 30 in thedirection of arrow 31. The added stiffness and rigidity offered byenlarged side seal portion 80 is provided at a point of optimaleffectiveness to react in an appropriate manner to forces applied toslider 30 and to overcome any resistance of the tracks 24, 26 to resumea mating, interlocked condition as the fastener tracks are interlocked.Those skilled in the art will appreciate that the “rolling resistance”or dynamic resistance to movement of slider 30 is oftentimes lower thanthe initial static resistance, opposing movement of the slider away fromthe fully opened or parked position shown, for example, in FIG. 4.

[0086] The added stiffness and rigidity imparted to the flexible package10 and especially panels 12, 14 by enlarged side seal portion 80 resultsin other advantages when lightweight panels 12, 14 are employed. Forexample, panels of the single polyolefin type where no laminate film(such as PET or NYLON) is used to stiffen and support the support panel,have oftentimes excluded the use of sliding zippers, since minimumstiffness and rigidity needed to operate a fastener slider was notavailable. However, with-enlarged side seal portions according toprinciples of the present invention, adequate stiffness is provided,even for lightweight, so-called “single” films.

[0087] As indicated in FIG. 10, flanges 72, 74 are joined to respectivepanels 12, 14, preferably at their lower ends, so as to prevent productfrom entering between flange 72 and panel 12, as well as between flange74 and panel 14. In certain applications this may not be a criticalrequirement. In FIG. 10, the upper portion of panel 12 is shown forillustrative purposes as spaced from the lower end of flange 72. Inpractice, it is generally preferred that this spacing be eliminated,with panel 12 being in intimate contact with flange 72. Similarly, anygap between panel 14 and the lower end of fastener flange 74 ispreferably eliminated. Although it is most preferred that the peelableseal be formed by joining panel 14 to fastener flange 72, the peelableseal, preferably a hermetic seal, can be formed between the fastenerflanges 72, 74 or directly between the panels 12, 14, although thesealternative constructions are less preferred than the arrangement shownin FIG. 10.

[0088] Turning now to FIG. 13, flexible package 10 is shown constructedwith the panels 12, 14, side seal 22, upper enlarged side seal portion80 and fastener tracks 26, 28, as described above. The fastener tracks26, 28 are preferably joined to flanges 72, 74 (not visible in FIG. 13).FIG. 13 schematically illustrates commercial fabrication of flexiblepackage 10. As will be appreciated by those skilled in the art,practical commercial assembly requires recognition of tolerances of theequipment and materials used to construct a viable commercial product.For example, tracks 26, 28 are ultimately mechanically coupled to panels12, 14 using conduction heat seal tooling. A gap 110 shown in FIG. 13represents the tolerance range or margin of error for tool alignmentused to secure the fastener tracks 26, 28. As mentioned, it is preferredthat the upper end of enlarged side seal portion 80 be spaced below thelower ends of the fastener tracks, such as the lower end 26 a offastener track 26 visible in FIG. 13. Further, it is preferred that thegap g continue beyond the end 56 of slider 30.

[0089] A gap 116 represents a tolerance range or margin of error for thedesired positioning of the upper end of enlarged side seal portion 80,to provide clearance for the bottom edge of slider 30. As illustrated inFIG. 13, the upper end of enlarged side seal portion 80 falls at anoutermost limit of its tolerance range. Preferably, the upper end ofenlarged side seal portion 80 is within the gap 116, rather than to oneend thereof. The gap 116 also accounts for any cant or angularmis-positioning or mis-alignment where the upper end of side seal 80 maybe angled slightly from a position parallel to the fastener tracks, asmay be encountered in a practical commercial environment.

[0090] A band 120 shown in FIG. 13 represents a conduction heat seal ofthe fastener flange to the panels 12 or 14. This conduction heat seal120 provides the principal mechanical attachment of the fastener trackassembly to the package panels. Band 36 is the peelable seal, preferablya hermetic seal, between panel 14 and fastener flange 72. A gap 124represents the desired production spacing between production seal 120and peelable seal 36. The remaining band 128 represents the productiontolerance range or margin of error for positioning of peelable seal 36with respect to the package panels.

[0091] In one commercial embodiment, flexible package 10 comprises aplastic bag having a width of approximately 6.5 inches from side edge toside edge and a total overall height of approximately 10.75 inches. Thefastener tracks 26, 28 have a height of approximately 4 millimeters,with gaps 110, 116 each having a height of 2 millimeters. As shown inthe upper right hand corner of FIG. 13, stop 68 projects a distance uabove the top edge of the fastener tracks. In FIG. 13, only the top edge26 b is visible. With reference to FIG. 10, the upper ends of panels 12,14 are preferably spaced a distance p from the bottom edges of thefastener tracks, ranging between 2 and 3 millimeters. The conductionheat seal 120 and the peelable seal 36 each have a height of 6millimeters, and gap 124 located between the two, has a height of 2millimeters. The desired spacing between conduction heat seal 120 andpeelable seal 36 has a maximum value of 2 millimeters and a minimumvalue required to prevent overlap of the conduction heat seal andpeelable seal. The side seal 22 has a width ranging between 3 and 8millimeters and the stop 68 has a width (see reference character d inFIG. 1) ranging between 2.0 and 8.0 mm. As can be seen with reference toFIG. 13, the upper end of side seal 22 is spaced a substantial distancebelow the upper edge of the flexible package. This spacing rangesbetween a minimum value equal to the combined height of the fastenertracks and gap 110, and a maximum value equal to the combined height ofthe fastener tracks, gap 110 and gap 116.

[0092] Referring to FIG. 14, several alternative features are shown withreference to a flexible package 130. The right hand portion of flexiblepackage 130 is identical to flexible package 10, described above, exceptfor the addition of a peg hole 132 formed in the enlarged side sealportion 80. Flexible package 130 has a left side seal 20 as describedabove with respect to FIG. 1. However, in the flexible package 130, theupper end of side seal 20 is enlarged at 138 in a manner similar to thatof enlarged side seal portion 80. An optional peg hole 140 is formed inthe enlarged side seal portion 138. Although the peg holes 132, 140 areshown having a circular shape, virtually any shape (e.g., oval) can beused, as well. Peg holes 132, 140 can be formed by punching before orafter the side seals are fully formed, it being preferred that the upperends of the side seals provide a complete sealing of the panels andother components of the flexible package. It will be appreciated bythose skilled in the art that the holes add heat relief to the enlargedside seal portion. This helps preserve the uniformity of the taperedarea and of the dimensioning of gap g, as well as the uniformity ofshrinkage which helps control manufacture on a production basis. Ifdesired, the heat sealing die can be made hollow in the region of thepeg holes, even in the absence of peg hole features to attain furtherheat relief advantages. It may also be preferable in some instances toform the peg holes 132, 140 as part of the formation of the side sealsusing, in effect, a thermal cutting or thermal punching technique. Withthe inclusion of two peg holes 132, 140, flexible package 130 canprovide an improved presentation of art work or other indicia carried onthe panels of the flexible package.

[0093] It is generally preferred that textual and graphic information beoriented generally perpendicular to the side edges of the flexiblepackage. If only one peg hole is provided, the package will tend to hangrotated in a vertical plane, according to the distribution of productwithin the flexible package. With support given to two peg holes 132,140, the flexible package is oriented in an upright position, making iteasier to read the text and graphical information carried on thepackage. If desired, the text and graphical information printed on therear panel can be inverted so that a consumer can “flip” the package toinspect the rear panel, without having to remove the package from thesupport pegs passing through peg holds 132, 140.

[0094] Although the package opening, fastener tracks and relatedfeatures are shown at the upper end of the flexible package, the presentinvention is intended to cover arrangements in which the opening andrelated structure is provided on the side or bottom of the flexiblepackage.

[0095] Referring now to FIGS. 15-25 and initially to FIG. 25, animproved package according to principles of the present invention, isshown. Package 199 includes the features of flexible package 10,described above and in addition includes a shroud portion 204 extendingabove line of weakness 208 formed in panels 12, 14. Line of weakness 208can be formed using available conventional techniques, and is preferablyformed, using laser scoring techniques. Preferably, line of weakness 208extends across the width of flexible package 199, from one side edge tothe other. As shown in FIG. 25, line of weakness 208 extends to edge 18,located at side seal 22. If desired, side seal 2 can be replaced by sideseal 20.

[0096] Preferably, shroud 204 is made for easy tear-away removal in anintuitive manual operation not requiring special directions. Preferably,a notch 210 is formed in edge 18, and is located slightly above stop 68.An optional angled or diagonal line of weakness 212 extends from notch210 to an opening 214 which surrounds slider 30. Opening 214 isillustrated as a rectangle with rounded corners. Opening 214 can howevertake on other shapes, such as that of a circle or teardrop, for example.Opening 214 relaxes the strain in the shroud portion of the flexiblepackage caused by relatively large-sized slide members. It is preferredthat the opening 214 be formed in the web prior to joining with fastenertracks. Accordingly, careful registration of the opening 214 is neededto insure the desired finished flexible package is produced.

[0097] Preferably, slider 30 is located at a fully closed position alongthe fastener tracks and is surrounded by opening 214 at the closedposition. In order to gain access to the package contents, a user graspsthe upper edge of shroud 204 causing an initially tearing at notch 210.Tearing continues along diagonal line 212 and enters opening 214,continuing along opening 214 to line 208. With continued tearing acrossthe width of package 199, the shroud 204 is removed, leaving a packagesubstantially similar to the packages described above in FIGS. 1-14.

[0098] Referring again to FIG. 25, shroud 204 includes an upper fin seal220 and a side fin seal portion 222. Preferably, the upper fin seal 220inside fin seal 222 are formed in separate sealing operations and aremade to slightly overlap one another for package integrity and sealingof the package interior. The bottom of side fin seal 222 is terminatedat or slightly above end stop 68. It is most preferred that side finseal 222 be terminated slightly above end stop 68 to avoid interferingwith the controlled formation of the end stop which, as pointed outabove, has a shape and position providing novel advantages. Notch 210 inthe preferred embodiment shown in FIG. 25 is formed at the lower end ofside fin seal 222. If desired, notch 210 could be formed in a gapbetween end stop 68 and a side fin seal shortened with respect to theside fin seal illustrated in FIG. 25.

[0099] Turning now to FIGS. 15-18 a flexible package 230 is shown.Package 230 is substantially identical to package 199 described above,except that opening 214 does not directly communicate with diagonal line212. Tearing of package 230 to remove shroud 204 is initiated at notch210 and continues along diagonal line 212 to a point of intersectionwith line of weakness 208. If desired, the portion of weakness line 208designated by reference numeral 232, line between diagonal line 212 andedge 18 can be omitted, if desired. Further, weakening line 208 anddiagonal line 212 can be formed in a single operation using conventionaltechniques such as laser cutting. As a further alternative, diagonalline 212 can be made to curve either along its entire length, or at thepoint of intersection with weakening line 208. FIG. 15 shows a centralpeg hole 234 is formed in upper fin seal 220.

[0100] Referring now to FIG. 19, flexible package 240 is substantiallyidentical to flexible package 230, except for the omission of opening214. Arrangement of FIG. 19 is preferably employed where the width ofslider 30 is reduced, or the shroud 204 is sufficiently flexible or hasan enlarged cross section so as to completely enclose slider 30 withoutrequiring an opening to relax tension in the material forming theshroud.

[0101] Referring now to FIG. 20, a cross section of flexible package 199is shown. Preferably, shroud 204 is formed as a continuous integralextension of panels 12, 14, the upper free edges of which are joinedtogether to form upper fin seal 220.

[0102] Referring to FIG. 21, exemplary tooling to form the package 199are shown. For example, a pair of upper seal bars 250 form upper finseal 220 while a pair of intermediate seal bars 252 join panels 12, 14to fastener flanges 72, 74. Lower seal bars 254 form the peel seal 36and weld band 78 (FIG. 20). The bottom of package 199, as is preferred,with the other flexible packages shown herein, is formed by a dead fold258.

[0103] Referring now to FIG. 22, a flexible package 260 is substantiallyidentical to flexible package 230 of FIG. 18, except for a curved lineof weakness 264 joining notch 210 with weakening line 208.

[0104]FIG. 23 shows a flexible package 270 similar to that of flexiblepackage 230, except that a large or tapered side seals are provided ateach side of the package. Peg holes 132, 140 are formed in the taperedside seal portions and if desired an optionally central peg hole 234 canbe formed in upper fin seal portion 220. As with the other embodimentsshown herein, it is generally preferred that the enlarged or taperedside seal portions stop short of the line of weakness 208.

[0105]FIG. 24 is a cross-sectional view of an optional flexible package280 substantially identical to flexible package 199, described above,except that a shroud member 282 is separately formed from panels 12, 14and is joined to the upper ends of the panels by conventional welding orother joining techniques. Most preferably, shroud 282 is joined to theupper ends of panels 12, 14 at the point of sealing with flanges 72, 74.The weakening line for removal of shroud of 282 can be formed eitherabove or below the point of sealing with remainder of the flexiblepackage.

[0106] It is generally preferred that textual and graphic information beoriented generally perpendicular to the side edges of the flexiblepackage. If only one peg hole is provided, the package will tend to hangrotated in a vertical plane, according to the distribution of productwithin the flexible package. With support given to two peg holes 132,140, the flexible package is oriented in an upright position, making iteasier to read the text and graphical information carried on thepackage. If desired, the text and graphical information printed on therear panel can be inverted so that a consumer can “flip” the package toinspect the rear panel, without having to remove the package from thesupport pegs passing through peg holds 132, 140.

[0107] Although the package opening, fastener tracks and relatedfeatures are shown at the upper end of the flexible package, theimproved flexible package is intended to cover arrangements in which theopening and related structure is provided on the side or bottom of theflexible package.

[0108] Turning now to FIG. 26 and following, apparatus for manufacturingimproved flexible packages having slide closures will now be described.As will be seen herein, the apparatus according to principles of thepresent invention, generally indicated at 300 employs a horizontal formfill seal arrangement with the in-line application of mated fastenertracks to a folded web. Apparatus 300 brings all of the requiredpackaging components together, for assembly, at the point of fill.

[0109] Referring to FIGS. 26 and 27, apparatus 300 includes a web supplyroll 304 providing a supply of web material 306 preferably comprising aconventional plastic packaging film. Web material 306 is advanced in thedirection of arrow 308. Punches 312 are schematically indicated and formthe openings 214 on opposed bag panel portions 12, 14 (see FIG. 15).Also, indicated in FIG. 29 are diamond shape cutouts 324 formed bypunches schematically indicated in FIG. 26 at 312. In FIG. 28 dottedline 318 indicates a crease or a fold line about which web 206 is foldedabout plow 330 (see FIG. 30) to form a “dead fold” 320 at the bottom ofthe finished bag, as shown in FIG. 29. The lines 326 running generallytransverse of web 206 indicate severing lines which divide one bagportion from another, the bag portions preferably being serially formedfrom a common web. After severing, the diamond cutouts 324 become pairsof opposed tear notches 210 shown for example in FIG. 39.

[0110] As mentioned, the web is initially formed so as to have a “deadfold” at its bottom end. If desired, processing can continue, eventuallyproducing separate bags having dead fold bottoms. As a preferredalternative, a gusset blade 340 can be employed in the mannerillustrated in FIG. 30 to form a gusset 342 in the bottom of the foldedweb. A W-shaped gusset or pleated bottom 342 is shown in greater detailin FIG. 31, and a “Delta-fold” gusset is shown in FIG. 33. The pleatedbottoms 324 are sealed as indicated in FIG. 32 using gusset sealing dies326. The dies 326 include upstanding saw tooth portions 328 configuredto seal the corners at side edges of the individual, separated bags.FIG. 33 shows the right-hand bottom corner of one bag with an angledseal edge 328 a.

[0111] Referring to FIGS. 26 and 30, a supply of mated fastener track210 (preferably comprising fastener tracks 26, 28) is supplied on roll350. Preferably, the fastener tracks include respective mounting flangeswhich overlie one another, and which extend along the mated fastenertracks. As can be seen, the mounting flanges are of unequal height (withthe food package viewed in an upright position) and extend from thefastener tracks different amounts. Further details concerning theconstruction and operation of the mated fastener tracks 210 and slider30 of the preferred embodiment may be obtained with reference to U.S.Pat. No. 6,047,450, the disclosure of which is herein incorporated byreference.

[0112] With additional reference to FIG. 26, the mated fastener track210 is fed through a roller guides 354 to enter a work station generallyindicated at 360 for forming stops 68 in the mated fastener track. Anadjacent work station 364 is provided for applying slide members 30 tothe fastener track.

[0113] Turning again to FIG. 26 and with additional reference to FIG.30, the prepared zipper track (with end stops and slider members) andthe folded web is brought together at fastener sealing station 400. FIG.35 shows a cross section of the web and fastener track prior to enteringthe sealing station. As shown, web 306 is folded into a general V-shapeto form opposed front and rear panels 402, 404 shown by a dead fold 406.The mated fastener track includes mated male and female track members26, 28 as described above, for example, with reference to FIG. 2. Trackmembers 26, 28 include a longer depending flange 12 and a shorterdepending flange 14, respectively. The side 14 a of flange 14 is joinedto the opposing interior surface 402 a of panel 402, as will be seenherein. Also, the lower surface portion 12 a is joined to panel surface402 a. The resulting joinder is diagrammatically illustrated in FIG. 44.After filling the flexible package, the outwardly facing surfaceportions 12 b and 12 c are joined to the opposing interior surface 404 aof panel 404.

[0114] The initial sealing of the prepared fastener track to the sidewall panels is carried out at station 400, preferably using five sealingtools. With reference to FIG. 36, four horizontal sealing tools arearranged in two pairs. The upper pair of sealing tools or dies includessealing die 410 adjacent panel 402 and sealing die 412 adjacent panel404. As will be seen herein, panel 402 preferably comprises the frontpanel of the flexible package while panel 404 comprises the opposed,rear side of the package. If desired, printing on the front and rearpanels 402, 404 could be interchanged one for the other.

[0115] Flange 14 is welded or otherwise joined to panel 402, but thelonger flange 12 remains unjoined the panel 404, to allow packagefilling as indicated in FIG. 44. Accordingly, sealing tool 410 is heatedto a temperature sufficient to cause joining of flange 14 to panel 402.Preferably, sealing is accomplished with the application of pressure andaccordingly sealing tool 412 is employed as a back up to sealing tool410. Preferably, both sealing tools 410, 412 are advanced toward oneanother, toward separator tool 416. At this stage of the assemblyoperation, it is preferred that sealing tool 412 be unheated, so as toprevent unwanted joinder of flange 12 to panel 404. In order to preventinadvertent sealing of fastener flanges 12, 14 by sealing tool 410, anunheated or cooled separator tool 416 is temporarily placed betweenflanges 12, 14. The joinder of the lower surface portion 12 a of flange12 and panel 402 forms a conventional peel seal whereas the joinder offlange 14 to panel 402 comprises a permanent seal.

[0116] As mentioned, it is preferred that flange 12 remain free ofjoinder with panel 404. However, it is desired that the lower portion ofinterior face 12 a be joined to panel 402. Accordingly, a pair ofsealing tools 420, 422 are advanced toward one another to bring flangeface 12 a in contact with the opposed interior surface 402 a of panel402. Accordingly, sealing tool 420 is heated to effect the desiredjoinder, but sealing tool 422 is either cooled or unheated to preventjoinder of flange 12 to panel 404.

[0117] Turning now to FIGS. 37 and 38, the joined web and preparedfastener tracks are advanced to the station 430. With reference to FIG.26, pairs of vertical sealing bars 432 cooperate to form side seals forthe flexible package. With reference to FIG. 28, side seals are formedalong lines 326 and with reference to FIG. 39, for example, the sideseals are indicated by 20, 22. FIG. 39 shows a completed flexiblepackage 200. Referring also to FIG. 25, it can be seen that the sideseals stop short of end stop 68, so as to provide an interveningspacing. In this manner, unwanted deformation of the end stop is avoidedas the side seals are formed. Accordingly, the vertical sealing bars 432are foreshortened with respect to the overall height of the flexiblepackage.

[0118] In the preferred embodiment, sealing bars 432 have heat loadingsoptimized for rapid assembly. Accordingly, it has been found desirableto add vertical cooling bars 434 at a downstream position to withdrawheat from the side seals. As mentioned above, the vertical sealing barsare foreshortened with respect to the overall height of the flexiblepackage. The vertical cooling bars could also be foreshortened in asimilar manner, since their function is to withdraw excess heatlingering after fusion of the side seals is completed. Alternatively,the cooling bars can extend upward beyond the side seals, if desired. Ifdesired, additional operations such as operating on the side panels withpunches 438 while the bag chain is temporarily stopped at station 430.Punches 438 can be employed, for example, to form side holes 132, 140 asshown in FIG. 14 or center hole 234 as shown, for example, in FIG. 15.If desired, the punching operation or other operations on the bag panelscan be carried out at station 450 located immediately downstream ofstation 430.

[0119] The lower portions of the flexible packages or bags are now fullyformed except for being connected together in serial succession in theform of a bag chain. Top filling and final sealing of the upper end ofthe flexible packages remains to be accomplished. If desired, thefilling and final, top sealing could be performed with the flexiblepackages serially connected in a bag chain. However, it is preferredthat the individual, partially formed flexible packages be separatedfrom one another at station 460.

[0120] With reference to FIG. 40, a series of knives 462 are employed tosever the bag chain to separate the empty, partially formed flexiblepackages at the end of the bag chain. Knives 462 are aligned so as tointersect the diamond-shaped openings 324, forming opposed V-shapednotches in side seals of adjacent flexible packages.

[0121] With reference to FIG. 39, for example, the notches formed areidentified by 210. It is generally preferred that V-shaped notches beformed in both side seals of the flexible packages. It is generallypreferred that the portions of the bag chain be supported prior to thesevering operation so as to maintain positional control of the severedflexible packages. Any of a number of conventional supports, such asvacuum operated suction cups can be employed for the purpose. Referringagain to FIG. 26, upper suction cups 468 are diagrammaticallyillustrated as spanning a pair of partially formed flexible packages.Preferably, a pair of suction cups 468 are employed, on opposite sidesthe flexible packages so that, by withdrawing the suction cups away fromone another, the upper ends of the flexible packages are opened. Atstation 480 interior portions of the flexible packages are inflated in agas flushing operation. Any suitable gas mixture could be employed,although it is generally preferred that an inert gas for gettering orotherwise displacing oxygen is employed. The separated, but incompletelyformed, flexible packages are advanced to filling station 500.

[0122] With reference to FIG. 44, filling is carried out usingconventional duck bill members 506. As schematically indicated in FIG.44, filling is carried out between the mated fastener track and panel404 with the bottom end 508 of the duck bill member being positioned at,or more preferably below flange 12. Referring to FIG. 43, a wide openingis provided by the duck bill arrangement nested within the openingformed between the zipper track and unjoined package panel. A relativelylarge size opening provided allows manufacturers to pour products intothe flexible packages at relatively high production line speeds, afeature attractive for mass production. The bottom end of flange 12 isschematically indicated in FIG. 44 as separated from panel 402. Thisarrangement is shown only for illustrative purposes, it being preferredthat the bottom end of flange 12 be joined to panel 402 to preventproduct from backing up above the peel seal. Positioning the bottom endof the filling apparatus beneath the peel seal for prevention ofunwanted product backup.

[0123] Turning now to FIGS. 41 and 42, the duck bill filling apparatus506 preferably has an articulated clam shell configuration. The bottomends 508 of the clam shell members are initially brought together so asto facilitate penetration into the interior of the flexible package.Once the filling apparatus is successfully inserted into the packageinterior, the filling apparatus is advanced until the lower ends 508 areplunged below the lower end of flange 12. The clam shell members arethen opened in the manner indicated in FIG. 42 to allow product 520 todrop into the flexible package. FIG. 43 shows the relatively largefilling opening it has made possible.

[0124] With filling of the flexible package being completed, a final topsealing operation is performed. With reference to FIG. 26, the flexiblepackages are advanced to station 600 containing conventional linearstretching apparatus 602. The flexible packages are then advanced to topsealing station 700 where the tops of the flexible packages seal and theshroud covering the mated zipper tracks is formed. With reference toFIGS. 45 and 46, three pairs of sealing bars are employed. The uppermostpair of sealing bars, identified by 710 to form the upper seal of theshroud indicated at 714 in FIG. 47.

[0125] The intermediate pair of sealing tools identified by 718 form thefusion seal between portion 12 b of flange 12 and panel 404. In order tocomplete the desired seal, the right-hand seal tool 718 is heatedwhereas the left-hand seal tool 718 is either unheated or cooled, toprovide backup so that pressure can be developed during the sealingoperation.

[0126] Finally, the lower end 12 c of flange 12 is joined to panel 404by a heated sealing tool 730 and a cooperating unheated or cooled sealtool 732. The resulting fusion seal is located laterally adjacent to thepeel seal described earlier with reference to flange portion 12 a.

[0127] A flexible package having a removable shroud covering a slidefastener has been shown. However, it should be readily apparent forthose skilled in the art that apparatus 300 can readily form, fill andseal flexible packages, such as those illustrated above in FIG. 1, forexample, which lack the shroud feature.

[0128] In addition to advantages described above with reference to theapparatus and method of filling flexible packages, it will beappreciated that the reclosable fastener tracks remain engaged or matedin the closed position throughout the forming, filling and sealing offlexible packages constructed according to principles of the presentinvention. This reduces the number of unit operations which wouldotherwise be required to open and reclose the fastener tracks. Further,the working surfaces of the fastener tracks are not exposed to product,dust and particles, which could interfere with reliable mating of thefastener tracks, and the ability of the slider member to move freely. Asindicated, for example, in FIG. 35 the longer flange is preferablyassociated with the male fastener track 26. As seen above, the longerflange, at its bottom end, forms a peel seal with a package panel. Theshorter flange, associated with the female fastener track 28 ispermanently joined to the package panel at an early stage of operation.The anchoring of the flange carrying the female track 28 onto the sidepanel of the bag and the application of the peelable seal on that sameside panel of the bag, associated with the male fastener track, providesa unique insulation of the reclosable top the flexible package duringthe filling and gas flushing. This construction creates a laminar flowof the purging gas (preferably nitrogen or carbon dioxide) thateffectively sweeps residual oxygen from the unfilled flexible package.As those skilled in the art of packaging foods and other products areaware, this feature of the invention is oftentimes found essential toprovide a modified atmosphere for packaging, which preserves thefreshness of the product being packaged.

[0129] The drawings and the foregoing descriptions are not intended torepresent the only forms of the invention in regard to the details ofits construction and manner of operation. Changes in form and in theproportion of parts, as well as the substitution of equivalents, arecontemplated as circumstances may suggest or render expedient; andalthough specific terms have been employed, they are intended in ageneric and descriptive sense only and not for the purposes oflimitation, the scope of the invention being delineated by the followingclaims.

What is claimed:
 1. A horizontal form-fill seal machine for the in-linemanufacturing of food packages having shrouded mated fastener trackswith slider closures, comprising: a supply of web material extending ina machine direction defining a serial succession of package sidewallsextending in the machine direction; a supply of mated fastener tracks,including a first track with a shorter flange mated to a second trackwith a longer flange; a folding member receiving said web material; aweb drive transporting said web material over said folding member in themachine direction, folding said web material into overlying side-by-sideportions, one against the other, to form a continuous succession offolded package portions extending in the machine direction and havingpairs of overlying first and second package sidewalls having overlyingfree edges with shroud portions at the free edges; a slider membermateable with said mated fastener tracks for movement along said matedfastener tracks in opposite directions to open and close said matedfastener tracks; a slider installation member inserting said slidermember onto said mated fastener tracks; fastener seal bars extending inthe machine direction, sealing a portion of each flange of said fastenertracks to said first sidewall, leaving the flanges free of attachment tothe second package sidewall; side seal bars extending at an angle tosaid machine direction, sealing portions of said package sidewallstogether to form respective side seals of the food package; a fillermember filling product into said package; sidewall sealing means sealingsaid second package sidewall to said second track flange; and a shroudsealing member sealing the free edges of said package sidewalls to forma shroud enclosing said fastener tracks, to thereby forming a completedfood package.
 2. The machine of claim 1 further comprising a separatingmember separating the completed food package from the folded packageportions.
 3. The machine of claim 1 wherein said fastener seal bars format least one peel seal and at least one permanent seal.
 4. The machineof claim 3 wherein a cavity is formed between the package sidewalls, themachine further comprising a package opening member upstream of saidfiller member to separate free edges of the package sidewalls inpreparation for a filling operation and a gas flushing member flushingthe cavity in preparation for a filling operation.
 5. The machine ofclaim 1 wherein said slider installation member is located upstream ofsaid fastener seal bars.
 6. The machine of claim 1 further comprising astop forming station through which said mated fastener tracks pass, tocrush a portion of said mated fastener tracks to form a stop member. 7.The machine of claim 6 wherein said stop forming station is locatedupstream of said slider installation member.
 8. The machine of claim 7wherein said slider installation member positions a slider memberimmediately downstream of the stop member.
 9. The machine of claim 1further comprising a funnel member having a free end insertable belowthe seals formed by said fastener seal bars.
 10. The machine of claim 7wherein said funnel member comprises a clam shell.
 11. The machine ofclaim 1 wherein two pairs of fastener sealing bars are providing forsealing the mated fastener tracks.
 12. The machine of claim 11 whereinthe mounting flanges extend from the fastener tracks different amounts,with one mounting flange having a greater height than the other, withthe food package viewed in an upright position.
 13. The machine of claim12 wherein the fastener track seal bars seal medial portions of saidpackage walls, intermediate the shroud portion at the top of the packagewalls and the bottom of the package walls.
 14. The machine of claim 13further comprising a notching member upstream of said folding member forforming a notch in the shroud portion.
 15. The combination of a shreddedcheese product and a vertical form-fill machine for the in linemanufacturing of food packages containing the cheese product and havingshrouded mated fastener tracks with slider closures comprising: a supplyof web material extending in a machine direction defining a serialsuccession of package sidewalls extending in the machine direction; asupply of mated fastener tracks, including a first track with a shorterflange mated to a second track with a longer flange; a folding memberreceiving said web material; a web drive transporting said web materialover said folding member in the machine direction, folding said webmaterial into overlying side-by-side portions, one against the other, toform a continuous succession of folded package portions extending in themachine direction and having pairs of overlying first and second packagesidewalls having overlying free edges with shroud portions at the freeedges; a slider member mateable with said mated fastener tracks formovement along said mated fastener tracks in opposite directions to openand close said mated fastener tracks; a slider installation memberinserting said slider member onto said mated fastener tracks; fastenerseal bars extending in the machine direction, sealing a portion of eachflange of said fastener tracks to said first sidewalls, leaving theflanges free of attachment to the second package sidewalls; side sealbars extending at an angle to said machine direction, sealing portionsof said package sidewalls together to form respective side seals of thefood package; a pair of shroud seal bars extending in the machinedirection, sealing the free edges of the package walls to form a closedshroud covering said fastener tracks; a filler member filling productinto said package; sidewall sealing means sealing said second packagesidewall to said second track flange; and a shroud sealing membersealing the free edges of said package sidewalls to form a shroudenclosing said fastener tracks, to thereby forming a completed foodpackage.
 16. A method of making a flexible package for food products,comprising the steps of: providing a supply of web material defining aserial succession of package sidewalls; paying out a first portion ofthe web material; providing a supply of mated fastener tracks, includinga first track with a shorter flange mated to second track with a longerflange; paying out a first portion of the mated fastener tracks;crushing a serial succession of spaced apart portions of said matedfastener tracks to form a serial succession of spaced apart slider stopportions; folding the web material to form a serial succession of foldedpackage portions, each folded package portion having overlapping firstand second package sidewalls with overlying free ends and shroudportions at the free ends, and intermediate portions spaced from theshroud portions; aligning the mated fastener tracks in-line with theintermediate portions; providing a supply of sliders; dispensing thesliders one at a time; inserting sliders on the mated fastener tracks;joining at least a part of the mated fastener tracks to the intermediateportion of said first package sidewall; forming a second fastener trackseal between a portion of the second fastener track flange and a portionof said first package sidewall adjacent the intermediate portionthereof; forming a permanent seal between the first fastener trackflange and the first package sidewall; forming transverse, side sealsfor each package portion to cooperate with said sidewalls to form apouch; severing the pouch from the web material and the mated fastenertracks to form a separate flexible package; separating the overlyingfree ends of the package portions to form an opening; filling the pouchwith product through the opening; joining one of the mated fastenertracks to the intermediate portion of said second package sidewall toclose the upper portion of the bag; and sealing free edges of thepackage sidewalls to form a shroud enclosing said mated fastener tracks.17. The method of claim 16 wherein the mated fastener tracks includedownwardly depending flanges and the step of the joining at least apartof the mated fastener tracks to the first package sidewall comprises thestep of providing a heat shield and inserting the heat shield betweenthe flanges while applying heat and pressure.
 18. The method of claim 16further comprising the step of forming a weakening line in at least oneof said sidewalls extending across the mated fastener tracks, to atermination point below said mated fastener tracks.
 19. The method ofclaim 18 further comprising the step of forming a tear line in at leastone of said sidewalls along a line extending below said mated fastenertracks and intersecting said termination point.
 20. The method of claim16 further comprising the step of forming a slider-receiving opening inat least one of said sidewalls to receive a portion of said slider. 21.The method of claim 16 wherein the step of inserting the slider isperformed before the step of joining the mated fastener tracks to thepackage sidewalls.
 22. The method of claim 16 wherein the step offorming a second fastener tracks seal comprises forming a peel seal.